The present invention relates to a moisture exchanger type ozone-generating apparatus which is equipped with an alternative switching type moisture exchanger.
FIG. 1 is a flow system diagram of the conventional moisture exchanger type ozone-generating apparatus.
In FIG. 1, the reference 1 designates a blower, 2-1, 2-2 designate adsorption towers in which an adsorbent such as silica gel is filled; 3-11 to 3-24 designate electromagnetic valves; 4 designates an ozone generator and 5 designates flow resistance.
The operation of the conventional apparatus of FIG. 1 will be illustrated.
The condition that the adsorption tower 2-1 is in a step of air-drying and the adsorption tower 2-2 is in a step of adsorbent-recovery will be illustrated. The electromagnetic vavles 3-11, 3-13, 3-22, 3-24 are opened and the other valves are closed.
A wet raw air compressed by the blower 1 is passed through the electromagnetic valve 3-11 into the adsorption tower 2-1 wherein moisture is adsorbed to form a dry air and the dry air is fed through the electromagnetic valve 3-13 to the ozone generator 4. When the dry air is passed through the ozone generator 4, a part of oxygen is ozonized by the silent discharge. If moisture is incorporated in the air, the amount of ozone generated, is decreased to cause corrosion of the ozone generator 4. Accordingly, it is necessary to use the dry air. The dry ozone-containing air is passed through the flow resistance 5 to reduce the pressure and is passed through the electromagnetic valve 3-24 to the adsorption tower 2-2, wherein the adsorbent is recovered. The dry ozone-containing air is converted to wet ozone-containing air and the wet ozone-containing air is passed through the electromagnetic valve 3-22 to the part for application of ozone.
When the adsorption function of the adsorbent in the adsorption tower 2-1 is reduced, the electromagnetic valves 3-12, 3-14, 3-21, 3-23 are opened and the electromagnetic valves 3-11, 3-13, 3-22, 3-24 are closed whereby the adsorption tower 2-2 is switched to the step of air-drying and the adsorption tower 2-1 is switched to the step of adsorbent-recovery
That is, the adsorption towers 2-1, 2-2 alternatively repeat the moisture adsorption and adsorbent recovery to attain the function as the moisture exchanger.
When silica gel is used as the adsorbent, the dry ozone-containing air is passed through the adsorption tower, the decomposition of ozone in the step of forming the wet ozone-containing air is quite small to be no trouble. In the apparatus of FIG. 2, the electromagnetic valves 3-11, 3-14, 3-21 3-24 of FIG. 1 are replaced to the check valves 3-11', 3-14', 3-21', 3-24' and the other parts are same with those of FIG. 1. The function is also same with that of FIG. 1.
The characteristics of the ozone generation of the conventional apparatus shown in FIGS. 1 and 2, are shown in FIG. 3.
In FIG. 3, the reference C.sub.1 designates the ozone concentration in the dry ozone-containing air (C.sub.1 sampling in FIG. 1) discharged from the ozone generator.
The reference C.sub.2 designates the ozone concentration in the wet ozone-containing air (C.sub.2 sampling in FIG. 1) discharged from the adsorption tower.
The decomposition of ozone in the adsorption tower is not substantially found. Accordingly, C.sub.2 is same with C.sub.1 in the normal condition, however, C.sub.2 is temporarily decreased to zero at the step of switching the adsorption tower. When silica gel is used as the adsorbent, silica gel adsorbs about 0.002 wt.% of ozone (at ozone concentration of 12 g/m.sup.3) at room temperature. When the dry ozone-containing air is passed to the silica gel which was used for air-drying, by switching the valves, C.sub.2 is decreased until the saturation of the ozone adsorption in the silica gel.
On the other hand, when the silica gel which adsorbed ozone at the recovery, is used for air-drying, at the beginning, the ozone adsorbed in the silica gel is desorbed to incorporate the ozone in the dry raw air to increase C.sub.1.
As stated above, the disadvantage of the conventional apparatus is to suddenly decrease the ozone concentration in the wet ozone-containing air as shown in FIG. 3 even though the period is short at the switching operation of valves.